1. Field of the Invention
The present invention relates to a sheet processing apparatus for conveying and processing sheets and a method of controlling the same, a sheet processing method, and storage media therefor.
2. Description of the Prior Art
In a conventional sheet processing apparatus that performs processing operations such as conveyance, stacking, sort and so forth, upon sheets discharged from an image forming apparatus or the like, in order to avoid a degradation in the overall processing efficiency of relatively time-consuming sheet processing operations on a downstream side of the apparatus as best represented by a binding operation upon a sheet bundle, recently, it has been proposed to provide a turnout for storing sheets in the conveyance path where the conveyance of sheets is temporarily stayed so that a plurality of sheets consisting of the stored sheets and other sheets subsequently conveyed from an upstream side of the apparatus are conveyed together simultaneously. In this way, an ample time can be secured for processing sheets on the downstream side, to thereby avoid degraded overall processing efficiency.
However, when special sheets such as cover sheets, thick paper sheets, thin paper sheets, tabbed sheets, colored sheets or other sheets that have different attributes from those of ordinary sheets are conveyed from an inserter to the turnout, these different attributes give rise to various problems. In the case of thick paper sheets, for example, the gap of the conveyance path may be narrowed due to the thickness of the sheets, or the thick paper sheet(s) may be pushed at the turnout to become curled and this curling deformation in turn may make the sheet(s) further thicker and further narrow the gap of the conveyance path, leading to an increase of the conveyance load and eventually giving rise to a paper jam. In the case of colored sheets, for example, the colored sheets may also be deformed into a curled shape and may narrow the gap between the sheets and conveyance path at the turnout or in subsequent discharge of the sheets. As a result, conveyance rollers and the like are forced to exert a strong conveyance load on the sheets so that traces of the rollers may be formed on the colored sheets.
It is an object of the present invention to provide a sheet processing apparatus and a method of controlling the same, a sheet processing method, and storage media therefor, which overcome the above described problems.
It is an object of the present invention to provide a sheet processing apparatus and a method of controlling the same, a sheet processing method, and storage media therefor, which are capable of achieving high quality processing and maintaining high productivity without giving rise to problems such as sheet jam or damage of sheets even when various sheets having different attributes are conveyed.
To attain the above objects, according to a first aspect of the present invention, there is provided a sheet processing apparatus comprising a conveyance path, a discharging port, conveyance means for conveying sheets along the conveyance path to the discharging port, sheet staying means for temporarily staying the sheets on the conveyance path, sheet type determining means for determining whether each of the sheets conveyed by the conveyance means is a special sheet or not, and sheet staying number limiting means for limiting a number of sheets to be stayed by the sheet staying means when each of the sheets conveyed by the conveyance means is the special sheet.
Preferably, the sheet processing apparatus according to the first aspect further comprises sheet staying number detecting means for detecting a number of sheets stayed by the sheet staying means, and wherein the sheet staying number limiting means comprises determining means for determining based on detection results of the sheet staying number detecting means whether the number of sheets stayed by the sheet staying means has reached a predetermined number that is set in advance in correspondence with the special sheet or not, and control means for causing conveyance of the sheets stayed by the sheet staying means by the conveyance means to be resumed when the number of sheets stayed by the sheet staying means has reached the predetermined number.
Preferably, when each of the sheets conveyed by the conveyance means is the special sheet, the sheet staying number limiting means inhibits staying of the sheets conveyed by the conveyance means by the sheet staying means.
Alternatively, the sheet processing apparatus according to the first aspect further comprises sheet staying number detecting means for detecting the number of sheets stayed by the sheet staying means, and wherein the sheet staying number limiting means comprises determining means for determining based on detection results of the sheet staying number detecting means whether the number of sheets stayed by the sheet staying means has reached a maximum number that is set in advance in correspondence with an ordinary sheet or not, and control means for causing conveyance of the sheets stayed by the sheet staying means by the conveyance means to be resumed when the number of sheets stayed by the sheet staying means has reached the maximum number.
More preferably, the sheet processing apparatus according to the first aspect further comprises sheet position detecting means for detecting a position of each of the sheets on the conveyance path, and wherein the control means temporarily keeps the conveyance means on standby to suspend conveyance of the sheets stayed by the sheet staying means by the conveyance means when the sheet position detecting means detects presence of at least one sheet downstream of the sheet staying means.
In the sheet processing apparatus according to the first aspect, the special sheet is a sheet selected from the group consisting of a sheet from a set tray, a sheet designated as a cover sheet, a sheet designated as a thick paper sheet, a sheet designated as a thin paper sheet, a tabbed sheet, and a colored sheet.
To attain the above objects, according to a second aspect of the present invention, there is provided a sheet processing method for use in a sheet processing apparatus including a conveyance path, a discharging port, conveyance means for conveying sheets along the conveyance path to the discharging port, sheet staying means for temporarily staying the sheets on the conveyance path, the method comprising the steps of determining whether each of the sheets conveyed by the conveyance means is a special sheet or not; and limiting a number of sheets to be stayed by the sheet staying means when each of the sheets conveyed by the conveyance means is the special sheet.
Preferably, in the sheet processing method according to the second aspect, the step of limiting the number of sheets to be stayed by the sheet staying means comprises limiting the number of sheets to be stayed by said sheet staying means by detecting the number of sheets stayed by the sheet staying means, determining whether the number of sheets stayed by the sheet staying means has reached a predetermined number that is set in advance in correspondence with the special sheet or not, and causing conveyance of the stayed sheets to be resumed when the number of sheets stayed by the sheet staying means has reached the predetermined number.
Preferably, the step of limiting the number of sheets to be stayed by the sheet staying means comprises limiting the number of sheets to be stayed by said sheet staying means by inhibiting staying of the sheets conveyed by the conveyance means by the sheet staying means when each of the sheets conveyed by the conveyance means is the special sheet.
Alternatively, the sheet processing method according to the second aspect comprises the steps of detecting the number of sheets stayed by the sheet staying means, determining based on detection results of the step of detecting the number of sheets whether the number of sheets stayed by the sheet staying means has reached a maximum number that is set in advance in correspondence with an ordinary sheet or not, and causing conveyance of the sheets stayed by the sheet staying means by the conveyance means to be resumed when the number of sheets stayed by the sheet staying means has reached the maximum number.
Preferably, the sheet processing method according to the second aspect further comprises the steps of detecting a position of each of the sheets on the conveyance path, and keeping the conveyance means on standby to suspend conveyance of the sheets stayed by the sheet staying means by the conveyance means when the step of detecting the position of each of the sheets detects presence of at least one sheet downstream of the sheet staying means.
In the sheet processing method according to the second aspect, the special sheet is a sheet selected from the group consisting of a sheet from a set tray, a sheet designated as a cover sheet, a sheet designated as a thick paper sheet, a sheet designated as a thin paper sheet, a tabbed sheet, and a colored sheet.
To attain the above objects, according to a third aspect of the present invention, there is provided a sheet processing apparatus which conveys a sheet from an upstream side to a downstream side of the apparatus, comprising sheet staying means for executing a sheet staying process to the sheet from the upstream side, to be conveyed to the downstream side, and control means for inhibiting the sheet staying process of the sheet staying means in accordance with a type of the sheet from the upstream side, to be conveyed to the downstream side via the sheet staying means.
Preferably, the control means causes the sheet conveyed from the upstream side to the downstream side via the sheet staying means, without being stayed by the sheet staying means, in accordance with the type of the sheet from the upstream side, to be conveyed to the downstream side via the sheet staying means.
In a typical example of the third aspect, the sheet from the upstream side includes an ordinary recording sheet, and a special recording sheet different in type from the ordinary recording sheet, and wherein the control means permits the sheet staying process of the sheet staying means if the sheet from the upstream side, to be conveyed to the downstream side, is the ordinary recording sheet, and inhibits the sheet staying process of the sheet staying means if the sheet from the upstream side, to be conveyed to the downstream side, is the special recording sheet different in type from the ordinary recording sheet.
Preferably, the special recording sheet includes at least one of a cover sheet, a tabbed sheet, a thick paper sheet, a thin paper sheet, and a colored sheet.
Preferably, the sheet staying means includes a roller capable of having at least one sheet wound thereon.
More preferably, the roller is capable of having a plurality of sheets wound thereon.
Still more preferably, the roller is capable of having the plurality of sheets wound thereon with each sheet being displaced from a preceding one in a direction of conveyance of the sheets.
Preferably, the sheet processing apparatus according to the third aspect conveys the sheet from the upstream side toward a loading means, arranged on the downstream side, for loading the sheets therein.
Preferably, the control means causes the sheet staying process to be executed by the sheet staying means if a sheet of another group, different from the sheet from the upstream side, is already loaded in the loading means.
More preferably, the control means causes the sheet staying means to stay the sheet from the upstream side until the sheet of another group already loaded in the loading means is removed from the loading means, and causes conveyance of the sheet stayed by the sheet staying means to be resumed when the sheet of another group has been removed from the loading means.
Advantageously, the control means inhibits the sheet staying process of the sheet staying means regardless of the type of the sheet from the upstream side, if a sheet of another group, different from the sheet from the upstream side, is not loaded in the loading means.
Also preferably, the sheet staying means is capable of staying a plurality of sheets, and wherein the control means causes conveyance of the sheets stayed by the sheet staying means to the downstream side to be resumed in accordance with a number of the sheets stayed by the sheet staying means.
To attain the above objects, according to a fourth aspect of the present invention, there is provided a sheet processing apparatus which conveys sheets from an upstream side to a downstream side of the apparatus, comprising sheet staying means for executing a sheet staying process to the sheets from the upstream side, to be conveyed to the downstream side, and control means for controlling a number of sheets to be stayed by the sheet staying means in accordance with a type of the sheets from the upstream side, to be conveyed to the downstream side via the sheet staying means.
Preferably, in the sheet processing apparatus according to the fourth aspect, the sheets from the upstream side include an ordinary recording sheet, and a special recording sheet different in type from the ordinary recording sheet, and wherein the control means controls the number of the special recording sheet to be stayed by the sheet staying means to a number less than the number of the ordinary recording sheet to be stayed.
To attain the above objects, according to a fifth aspect of the present invention, there is provided a control method for controlling a sheet processing apparatus which conveys a sheet from an upstream side to a downstream side of the apparatus, and includes sheet staying means for executing a sheet staying process to the sheet from the upstream side, to be conveyed to the downstream side, the method comprising the step of inhibiting the sheet staying process of the sheet staying means in accordance with a type of the sheet from the upstream side, to be conveyed to the downstream side via the sheet staying means.
To attain the above objects, according to a sixth aspect of the present invention, there is provided a machine readable storage medium storing a program for causing a sheet processing apparatus which conveys a sheet from an upstream side to a downstream side, and includes sheet staying means for executing a sheet staying process to the sheet from the upstream side, to be conveyed to the downstream side, to execute the step of inhibiting the sheet staying process of the sheet staying means in accordance with a type of the sheet from the upstream side, to be conveyed to the downstream side via the sheet staying means.
To attain the above objects, according to a seventh aspect of the present invention, there is provided a control method for controlling a sheet processing apparatus which conveys a sheet from an upstream side to a downstream side, and includes sheet staying means for executing a sheet staying process to the sheet from the upstream side, to be conveyed to the downstream side, the method comprising the step of controlling a number of the sheet to be stayed by the sheet staying means in accordance with a type of the sheet from the upstream side, to be conveyed to the downstream side via the sheet staying means.
To attain the above objects, according to an eight aspect of the present invention, there is provided a machine readable storage medium storing a program for causing a sheet processing apparatus which conveys sheets from an upstream side to a downstream side of the apparatus and includes sheet staying means for executing a sheet staying process to the sheet from the upstream side, to be conveyed to the downstream side, to execute the step of controlling a number of the sheet to be stayed by the sheet staying means in accordance with a type of the sheet from the upstream side, to be conveyed to the downstream side via the sheet staying means.
The above and other objects and features of the present invention will become more apparent from the following detailed description taken in conjunction with the accompanying drawings.